Using a sophisticated simulation, engineers have studied the complex evolution of a head-on collision between two high-speed water droplets, each about 400 micrometers in diameter, or about twice the thickness of a human hair. This snapshot from the simulation depicts the droplet dynamics moments after their collision, just as they are beginning to break up into smaller droplets.

Apparent in the image are an expanding "sheet" of liquid caused by the collision, and a thicker "rim" at the outer edge of this sheet. Ligaments of water, formed by the destabilization of the liquid rim, stretch across the radius of the sheet. One can also see small droplets generated by the end-pinching of these ligaments.

The researchers' simulations allowed them to describe and explain the expansion and contraction within the liquid sheet, as well as the fragmentation of the liquid rim and the sizes of the droplets that result from this fragmentation. The rich information obtained from these numerical simulations can be used to establish a physical link between the behavior of the water droplets and their statistical characteristics during an impact.

Reporters and Editors

This image can be freely reproduced with the accompanying credit: "Xiaodong Chen and Vigor Yang (School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA)."